1. Field
The following description relates to a streaming technology in a peer-to-peer (P2P) network, and more particularly, to a system for reducing streaming delay in a P2P network.
2. Description of the Related Art
Streaming technology may be used to play images, sound, animation files, and the like, in real time on the Internet, instead of downloading the entire file to a hard disk drive and then playing the file. When streaming data, before a file is completely transmitted, a user's browser or plug-in program begins to execute the data. Accordingly, the time it takes for the file to begin playing is reduced and the capacity of the hard drive is not substantially affected.
With the development of peer-to-peer (P2P) technology, P2P-based streaming services have become popular such as PPLIVE® and PPStream. In a P2P network for the streaming service, a user node may operate as a server to provide contents by sharing the load of a contents providing server. In doing so, the user node lightens the resource burden of the contents providing server. Even when a large number of users simultaneously use the service, for example, when an international sports match or a presidential inauguration are broadcast through the streaming service, the streaming service can be sufficiently provided without overextending a system. The streaming service using P2P technology can reduce costs for service providers and provides low service charge and a high quality of experience (QoE) for users.
However, the streaming service using P2P technology does not guarantee quality of service. For example, a transmission delay that effects real-time streaming characteristics, that are critical in live broadcasts, needs to be resolved for P2P streaming technology. The time at which a user plays a specific location of content is determined by adding the transmission time to the time at which the server transmits a content portion at the location. This difference in playing time due to transmission is called a transmission delay time. The transmission delay is severe in the P2P streaming technology because the P2P network has a structure that increases the delay due to content packets being iteratively stored and transferred via several hops, unlike a server-client model in which contents are directly received from a server.